A fuel cell, in particular a solid polymer fuel cell, is highly expected to become as a next generation power generating system. It is advantageous that the solid polymer fuel cell has a lower operating temperature than that the other fuel cell type has, and is compact. Because of these benefits, the solid polymer fuel cell is promising as a home power supply or an automobile power supply. The solid polymer fuel cell has a layered structure that includes a hydrogen electrode, an air electrode, and a solid polymer electrolyte membrane held between these electrodes. To the hydrogen electrode and the air electrode, a fuel including hydrogen and oxygen or an air are supplied respectively, so that an electric power generated through an oxidation or reduction reaction in each of the electrodes is to be extracted. In addition, to both of the electrodes, a blend of a catalyst with a solid electrolyte to promote the electrochemical reaction is applied in general.
As the catalyst composing the above mentioned electrode, a platinum catalyst which carries a precious metal, in particular platinum, as a catalytic metal is widely used conventionally. This is because platinum as a catalytic metal has so high activity that the electrode reactions in both of the fuel electrode and hydrogen electrode are promoted.
Incidentally, in recent years, in order to reduce the consumed amount of platinum for cost reduction of the catalyst while ensuring the catalytic activity, case examples are increasing that examine an alloy catalyst which uses an alloy of platinum with another metal as a catalytic metal. In particular, a Pt—Co catalyst that has an alloy of platinum with cobalt as a catalyst particle is known as a catalyst capable of reducing the consumed amount of platinum while exhibiting a catalytic activity comparable to or higher than the platinum catalytic activity. In addition, in order to further improve the above mentioned Pt—Co catalyst, a ternary alloy catalyst is advised in which a third alloy element is alloyed (Patent Literature 1).